Fuel pumping apparatus

ABSTRACT

A fuel pumping apparatus for supplying fuel to an internal combustion engine includes an angularly movable cam, the setting of which is determined by a piston housing a servo-valve. The servo-valve is subjected to a control pressure and moves to admit or release fluid from the cylinder containing the piston. For this purpose, a port is provided which is controlled by a land on the servo-valve. The land is shaped so that on angular movement of the servo-valve, a variation in the setting of the piston will occur and thereby a variation in the setting of the cam.

United States tet 1191 1111 3,869,226

Sosnowski Mar. 4, 1975 FUEL PUMPING APPARATUS 3.552366 1/1971 Kemp 417/206 317581240 9/1973 Kemp 417 402 [75] Inventor: Stanislaw Jan Antoni Sosnowski,

London, England I Primary E,\aminerW1ll1am L. Freeh [73] Asslgnee: g' i Blrmmgham Attorney, Agent, or FirmHolman & Stern ng an [22] Filed: Sept. 12, 1973 [57] ABSTRACT [21] Appl. No.: 396,534

A fuel pumping apparatus for supplying fuel to an internal combustion engine includes an angularly movl Foreign Application Primity Data able cam, the setting of which is determined by a pis- Sept. 12, 1972 Great Britain 42272/72 ton housing a servo-valve. The servo-valve is subjected to a control pressure and moves to admit or release [52] U.S. Cl. 417/462 fluid from the cylinder containing the piston. For this [51] Int. Cl. F04) 19/02 purpose a port is provided which is cgntrolled by a [58] Field Of SearCh-. 3/ 139 Q, 139 land on the servo-valve. The land is shaped so that on 206112420 angular movement of the servo-valve, a variation in the setting of the piston will occur and thereby a varia- [56] References Cited tion in the setting of the cam.

UNITED STATES PATENTS 4 D F. 3,433,159 3/1969 Kemp 123 139 A0 5 rawmg &

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(51 HB H t an /11/ i 1111 19 1s 15 1726 i23 20 14273020 PATENTED MAR 41975 SHEET 1 BF 2 @w omkw 3 ON QM NM NM mm & Q Q Q PATENTEI] MAR 41975 sumanrz FUEL PUMPING APPARATUS BACKGROUND OF THE INVENTION This invention relates to liquid fuel pumping apparatus for supplying fuel to an internal combustion engine, the apparatus being of the kind comprising a plunger located within a bore, cam means for effecting movement of the plunger, a fluid pressure operable piston for adjusting the setting of the cam means, an axially movable servo-valve for controlling the application of fluid pressure to the piston, with said servo valve being subjected to a fluid control pressure generated within the apparatus, the apparatus also including a manual control whereby the quantity of fuel supplied to the engine at each injection stroke of the apparatus can be varied.

OBJECT AND SUMMARY OF THE INVENTION The object of the invention is to provide such an apparatus in a simple and convenient form.

According to the invention, an apparatus of the kind specified comprises a bore formed in the piston, said bore slidably accommodating said servo-valve, passage means conveying said fluid control pressure so that it can act on the valve in opposition to the force exerted by resilient means, a port formed in the wall of the bore and through which fluid can flow to and escape from the cylinder accommodating the piston, a control land on said servo valve for controlling fluid flow through said port, said servo valve and piston constituting a follow-up servo-system, means coupling said servo-valve with said manual control, said land being shaped so that angular movement of the servo valve will, for a given axial position of the servo valve, effect uncovering of the port thereby to cause axial movement of the piston and adjustment of said cam means.

One example of a liquid fuel pumping apparatus in accordance with the invention will now be described with reference to the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a section through a portion of the apparatus,

FIG. 2 is a section through part of the apparatus seen in FIG. 1,

FIG. 3 is a side view showing a modified form for part of the apparatus seen in FIG. 1, and

FIG. 4 is a side view of the pumping apparatus.

Referring to FIG. 1 of the drawings, there is provided a pump body in which is mounted a rotatable distributor member 9. The distributor member is arranged to be driven in timed relationship with the associated engine and formed in the distributor member is a transversely extending bore 8 in which is located a pair of pumping plungers 7. The pumping plungers, as the distributor member rotates, are moved inwardly by the action of cam lobes 11 formed on the internal periphery of an annular cam ring 12 which is located within the body 10.

This form of apparatus is well known and the transverse bore which is formed in the distributor member 9 communicates with a longitudinal passage 6 also formed within the distributor member and which at one point communicates with a radially disposed delivery passage extending to the periphery of the distributor member and at a position to register in turn with a plurality of outlet ports formed in the body. The outlet ports in use, are connected to the injection nozzles of the associated engine. The aforesaid longitudinal passage also communicates with a plurality of inlet passages and these are positioned to register in turn with an inlet port formed in the body and which communicates with a source of fuel. The inlet port is arranged to register with an inlet passage during the time when rollers actuating the plungers are free of the cam lobes 11 and during this time fuel flows into the transverse bore 8. The amount of fuel flowing into the bore and which is subsequently delivered by the apparatus, depends upon the setting of a manually adjustable member 13 which is seen in FIG. 4. As the inlet passage moves out of register with the inlet port the delivery passage moves into register with an outlet port and in addition, the plungers are moved inwardly by the action of the cam lobes. During such inward movement, fuel flows through the aforesaid outlet port to the associated engine and the cycle is repeated with each outlet port in turn receiving fuel at the appropriate time.

It is known practice in such forms of apparatus to effect angular movement of the cam ring 12 in order to adjust the timing of injection of fuel to the engine and for this purpose, the cam ring is coupled to a piston 14 I which is located within a tangentially disposed cylinder 15, one end of which is closed by a plug 16.

The piston is provided with a bore 17, one end of which is closed by a plug 18, with the plug 18 being disposed at the end of the piston adjacent the plug 16. Moreover, formed within the piston is a passage 19 which, at one end, breaks out onto the face of the piston adjacent the plug 16 and which, at its other end, communicates with a port 20 formed in the wall of the bore 17.

Located within the bore 17 is a servo-valve 21 having a groove 22 formed intermediate its ends. The groove 22 is in constant communication by way of a passage 23 formed in the piston, with a supply passage 24 which is formed in the body 10 and which communicates with a source of fluid under pressure. Conveniently, this is the outlet of a vane type feed pump located in the body 10 and which supplies fuel to the aforesaid inlet port.

The groove 22 is bordered on one side by a land 25 and on its other side by a head 26 and the portion of the bore intermediate the head 26 and the plug 18 is in constant communication with a source of fluid at a controlled pressure. Conveniently, the fluid is fuel obtained from the outlet of the feed pump and its pressure is controlled by valve means so that it varies in accordance with the square of the speed at which the distributor member is driven. The force exerted on the servovalve 21 by the control pressure is opposed by resilient means in the form of a coiled compression spring 27 and, in addition, the piston 14 is. loaded by a further coiled compression spring 28 in a direction towards the plug 16.

The servo-valve is provided with an extension 29 which is of semi-circular section and having its plane surface extending along the axis of the servo-valve. For co-operation with this surface, a :similar surface is defined on an extension 30 which is formed on the end of an angularly adjustable member 31 which is journalled for angular movement within a closure 32 for the other end of the cylinder 15. The member 31 is coupled to a lever 33 and as shown in FIG. 4, the lever 33 is coupled by means ofa link 34 of adjustable length to a further lever 35 mounted for angular movement about the same axis and connected to the manually adjustable member 13. The arrangment is such that when the member 13 is moved angularly to control quantity of fuel which is supplied to the engine, angular movement will be imparted to the lever 33 and thereby to the servo-valve 21. The co-operation of the extensions 29 and 30 is such that axial movement of the servo-valve can take place irrespective of its angular position. Moreover, alternative positions are provided on the lever 35 for the connection with the link 34. Adjustment of the length of the link 34 alters the timing relative to the setting of the member 13 and the effective length of the lever 35 alters the rate of angular movement of the servo-valve.

The mode of operation of the device will be described firstly assuming that the angular setting of the servo-valve remains constant. The axial position of the servo-valve depends upon the magnitude of the pressure applied to the end of the head 26 and in the event that this pressure increases, the servo-valve will move against the action of the spring 27 and thereby the land will uncover the port to the groove 22. This groove is supplied with fuel from the outlet of the feed pump and this fuel will flow through this port 20 along the passage 19 into the space between the piston and the plug 16. The fuel pressure will effect movement of the piston against the action of the spring 28 and thereby angular adjustment of the cam will take place. The piston will continue to move until the port 20 is recovered by the land 25. Conversely, if the pressure applied to the head of the servo valve decreases, the valve will move under the action of the spring and the port 20 will be exposed on the right hand side of the land 25. The space which accommodates the springs is connected to the inlet of the feed pump which is, of course, at a lower pressure. The spring 28 will therefore urge the piston 14 towards the plug 16 and fuel will flow along the passage 19 and through the port 20 and such flow will occur until the port 20 is again covered by the land. The servo-valve and piston therefore constitute a follow-up servo-system.

The land is axially stepped and has two sections which are axially displaced from each other. Both sections are of substantially the same axial length L, and it will be seen that depending on which section is covering the port 20, so the axial position of the piston will vary. it will be seen therefore that the timing of injection of fuel to the engine can be varied in accordance with the position of the manually operable lever 13 although it will be appreciated that in the example so far described, only two land portions are provided and therefore only two different settings are obtained. It will be appreciated however that more step sections could be provided and it will be further understood that the setting of the piston is always dependent on the magnitude of the control pressure.

ln the arrangement shown in FIG. 3a the-land 36 is of helicoidal form so that continuous adjustment of the axial position of the piston 14 is obtained as the servovalve 21 is moved angularly.

I claim:

1. A liquid fuel pumping apparatus for supplying fuel to an internal combustion engine, the apparatus being of the kind comprising a plunger located within a bore, cam means for effecting movement of the plunger, a fluid pressure operable piston for adjusting the setting of the cam means, an axially movable servo-valve for controlling the application of fluid pressure to the piston, said servo valve being subjected to a fluid control pressure generated within the apparatus, the apparatus also including a manual control whereby the quantity of fuel supplied to the engine at each injection stroke of the apparatus can be varied, a bore formed in the piston, said piston bore slidably accommodating said servo valve, passage means conveying said fluid control pressure so that it can act on the valve in opposition to the force exerted by resilient means, a port formed in the wall of the piston bore and through which fluid can flow to and escape from the cylinder accommodating the piston, a control land on said servo valve for controlling fluid flow through said port, said servo-valve and piston constituting a follow-up servo-system, means coupling said servo-valve with said manual control, said land being shaped so that angular movement of the servo-valve will, for a given axial position of the servo-valve, effect uncovering of the port thereby to cause axial movement of the piston and adjustment of said cam means.

2. An apparatus as claimed in claim 1 in which said land has at least two sections which are axially displaced from each other.

3. An apparatus as claimed in claim 1 in which said land is of helicoidal form.

4. An apparatus as claimed in claim 1 in which said servo valve is provided with an extension of semicircular section having its plane surface extending along the axis of the servo-valve, there being provided an angularly adjustable member having a further extension of semi-circular section, the plane surfaces of said extensions engaging with each other whereby angular movement of the member will effect angular movement of the servo-valve, while allowing relative axial movement of the servo-valve and member and link means coupling said member to said manual control.

5. An apparatus as claimed in claim 4 in which said link means includes a link of adjustable length. 

1. A liquid fuel pumping apparatus for supplying fuel to an internal combustion engine, the apparatus being of the kind comprising a plunger located within a bore, cam means for effecting movement of the plunger, a fluid pressure operable piston for adjusting the setting of the cam means, an axially movable servo-valve for controlling the application of fluid pressure to the piston, said servo valve being subjected to a fluid control pressure generated within the apparatus, the apparatus also including a manual control whereby the quantity of fuel supplied to the engine at each injection stroke of the apparatus can be varied, a bore formed in the piston, said piston bore slidably accommodating said servo valve, passage means conveying said fluid control pressure so that it can act on the valve in opposition to the force exerted by resilient means, a port formed in the wall of the piston bore and through which fluid can flow to and escape from the cylinder accommodating the piston, a control land on said servo valve for controlling fluid flow through said port, said servo-valve and piston constitutiNg a follow-up servo-system, means coupling said servo-valve with said manual control, said land being shaped so that angular movement of the servo-valve will, for a given axial position of the servo-valve, effect uncovering of the port thereby to cause axial movement of the piston and adjustment of said cam means.
 2. An apparatus as claimed in claim 1 in which said land has at least two sections which are axially displaced from each other.
 3. An apparatus as claimed in claim 1 in which said land is of helicoidal form.
 4. An apparatus as claimed in claim 1 in which said servo valve is provided with an extension of semi-circular section having its plane surface extending along the axis of the servo-valve, there being provided an angularly adjustable member having a further extension of semi-circular section, the plane surfaces of said extensions engaging with each other whereby angular movement of the member will effect angular movement of the servo-valve, while allowing relative axial movement of the servo-valve and member and link means coupling said member to said manual control.
 5. An apparatus as claimed in claim 4 in which said link means includes a link of adjustable length. 